Use genrule instead of cc_genrule in Android.bp

Since the proto compiler doesn't need .o files as input, we can use a
genrule instead of cc_genrule to run it.

BUG=70682781

Change-Id: I2bb74df3ce60edeb654574d21c51096f3fbb9395
diff --git a/tools/gen_android_bp b/tools/gen_android_bp
index 4134e5c..87c6a55 100755
--- a/tools/gen_android_bp
+++ b/tools/gen_android_bp
@@ -239,7 +239,7 @@
     """
     # Don't try to inject library/source dependencies into genrules because they
     # are not compiled in the traditional sense.
-    if module.type == 'cc_genrule':
+    if module.type == 'genrule':
         return
 
     # If the dependency refers to a library which we can replace with an Android
@@ -279,7 +279,7 @@
     GN actions are used to dynamically generate files during the build. The
     Soong equivalent is a genrule. This function turns a specific kind of
     genrule which turns .proto files into source and header files into a pair
-    equivalent cc_genrules.
+    equivalent genrules.
 
     Args:
         blueprint: Blueprint instance which is being generated.
@@ -303,11 +303,11 @@
     # generated files needs to declare two different types of dependencies --
     # source files in 'srcs' and headers in 'generated_headers' -- and it's not
     # valid to generate .h files from a source dependency and vice versa.
-    source_module = Module('cc_genrule', label_to_module_name(target_name))
+    source_module = Module('genrule', label_to_module_name(target_name))
     source_module.srcs.extend(label_to_path(src) for src in target['sources'])
     source_module.tools = ['aprotoc']
 
-    header_module = Module('cc_genrule',
+    header_module = Module('genrule',
                            label_to_module_name(target_name) + '_headers')
     header_module.srcs = source_module.srcs[:]
     header_module.tools = source_module.tools[:]
@@ -402,7 +402,7 @@
 
     for module in modules:
         module.comment = 'GN target: %s' % target_name
-        if module.type != 'cc_genrule':
+        if module.type != 'genrule':
             module.defaults = [defaults_module]
 
         apply_module_dependency(blueprint, desc, module, target_name)